Performance Of Maize Hybrids Research Articles

Identification of metabolic and protein markers representative of the impact of mild nitrogen deficit on agronomic performance of maize hybrids

IntroductionA better understanding of the physiological response of silage maize to a mild reduction in nitrogen (N) fertilization and the identification of predictive biochemical markers of N utilization efficiency could contribute to limit the detrimental effect of the overuse of N inputs.ObjectivesWe integrated phenotypic and biochemical data to interpret the physiology of maize in response to a mild reduction in N fertilization under agronomic conditions and identify predictive leaf metabolic and proteic markers that could be used to pilot and rationalize N fertilization.MethodsEco-physiological, developmental and yield-related traits were measured and complemented with metabolomic and proteomic approaches performed on young leaves of a core panel of 29 European genetically diverse dent hybrids cultivated in the field under non-limiting and reduced N fertilization conditions.ResultsMetabolome and proteome data were analyzed either individually or in an integrated manner together with eco-physiological, developmental, phenotypic and yield-related traits. They allowed to identify (i) common N-responsive metabolites and proteins that could be used as predictive markers to monitor N fertilization, (ii) silage maize hybrids that exhibit improved agronomic performance when N fertilization is reduced.ConclusionsAmong the N-responsive metabolites and proteins identified, a cytosolic NADP-dependent malic enzyme and four metabolite signatures stand out as promising markers that could be used for both breeding and agronomic purposes.

Genome-Wide Association Study for Maize Hybrid Performance in a Typical Breeder Population.

Maize is one of the major crops that has demonstrated success in the utilization of heterosis. Developing high-yield hybrids is a crucial part of plant breeding to secure global food demand. In this study, we conducted a genome-wide association study (GWAS) for 10 agronomic traits using a typical breeder population comprised 442 single-cross hybrids by evaluating additive, dominance, and epistatic effects. A total of 49 significant single nucleotide polymorphisms (SNPs) and 69 significant pairs of epistasis were identified, explaining 26.2% to 64.3% of the phenotypic variation across the 10 traits. The enrichment of favorable genotypes is significantly correlated to the corresponding phenotype. In the confident region of the associated site, 532 protein-coding genes were discovered. Among these genes, the Zm00001d044211 candidate gene was found to negatively regulate starch synthesis and potentially impact yield. This typical breeding population provided a valuable resource for dissecting the genetic architecture of yield-related traits. We proposed a novel mating strategy to increase the GWAS efficiency without utilizing more resources. Finally, we analyzed the enrichment of favorable alleles in the Shaan A and Shaan B groups, as well as in each inbred line. Our breeding practice led to consistent results. Not only does this study demonstrate the feasibility of GWAS in F1 hybrid populations, it also provides a valuable basis for further molecular biology and breeding research.

Agronomic performance of maize hybrids under Aspergillus flavus inoculation in Cameroon

Maize (Zea mays L.) is a major staple crop in most of the sub-Sahara Africa (SSA) region, constrained by a multitude of plant diseases, with the ear and kernel rots being the most widespread and difficult to manage on maize. The objective of this study was to access the agronomic performance of F1 maize hybrids exposed to Aspergillus flavus, under different agro-ecological conditions, in Cameroon. A total of 120 genotypes of maize, including four commercial hybrids, were evaluated under A. flavus infection at two sites; namely Bangangte in the Western Highlands and Mbalmayo, in the Bimodal Humid Forest Zone of Cameroon. The study was conducted during 2020 - 2021 cropping seasons. Results revealed that at Bangangte site, six (89343X88094, 88099X88094, 90204XExp 124, 89246X87036, TZI-5-1171XExp 124 and 90219X1368) out of the top 20 high yielding hybrids, had significantly high (p<0.001 tolerance (0% severity) to Aspergillus ear rot infection. At Mbalmayo site, eight (8923X88094, TZI-5-1171XExp124, 89343X88094, 90219X87036, 89243X87036, 87014X88094, TZSTR1150X87036 and 89248X88094) out of the top 20 high yielding hybrids also showed significant high (P<0.001) tolerance (0% severity) to Aspergillus ear rot infection. The interaction between hybrids and location was significant (P<0.05) for all measured traits, except ear height, grain texture, ear insect damage and husk cover (P>0.05). The pooled broad sense heritability of hybrids in the two locations varied from 5% for grain texture to 92% for days to 50% physiological maturity. Grain yield was negatively correlated with Aspergillus ear rot disease incidence and severity. Hence, promising high yielding maize hybrids with appreciable tolerance to Aspergillus ear rot disease could be selected among the tested genotypes.

Multi-Traits Selection of Maize Hybrids under Sole-Crop and Multiple-Crops with Soybean

Multi-trait selection is very helpful in plant breeding programs. This technique can select genotypes for specific traits. Yield performance of maize hybrids is influenced by genotype-by-environment interactions (GEIs). This requires multi-environmental testing to identify superior hybrids. The aims of this study were to: (1) select maize hybrids within favorable traits such as grain yield and yield attributes; (2) identify genotype and environment interactions (GEIs) within maize yield; (3) evaluate maize hybrids adaptability to four different locations in West Java; and (4) identify a representative environment for testing and developing new maize hybrids. Twenty-two maize hybrids were evaluated using a randomized block design repeated three times in each environment. The genotype by traits (GT) biplot showed that G3 maize hybrid was superior to ear weight (EW), ear weight without corn husk (EwoH), ear weight per plot (EWP), plant height (PH), ear diameter (ED), and 1000 seed weight (OSW) traits. The G22 maize hybrid was superior to ear weight without corn husk per plot (EwoP), ratio seed weight and ear weight without corn husk (RSEW), grain yield per ha (Y), seed weight (SW), and seed weight per plot (SWP) traits. Combined analysis of variance showed that genotype (G), environment (E), and their interactions (GEIs) had a significant effect on yield (p < 0.01) with contributions of 85.63%, 2.24%, and 12.13%, respectively. The combined stability measurement results and the GGE biplot reveal that G2 is a stable high-yield hybrid, while G4 and G16 are unstable high-yield hybrids. The most representative environment is Arjasari, with the sole-cropping system (ARJ M). This study reveals that the resulting maize hybrid can be useful as a substitute for commercial hybrids currently used. The stable high yield of maize hybrids can be recommended as new varieties with wide adaptation, while unstable high-yield hybrids can be recommended as varieties adapted to specific environments.

Predicting zinc‐enhanced maize hybrid performance under stress conditions

AbstractThe low yield potential of most biofortified maize is a barrier to its full adoption and reduces its potential to curb various macro‐ and micronutrient deficiencies highly prevalent in low‐income regions of the world, such as sub‐Saharan Africa (SSA). By crossing biofortified inbred lines with different nutritional attributes such as zinc (Zn), provitamin A and protein quality, breeders are attempting to develop agronomically superior and stable multi‐nutrient maize of different genetic backgrounds. A key question, however, is the relationship between the biofortified inbred lines per se and hybrid performance under stress and non‐stress conditions. In this study, inbred line per se and testcross performance were evaluated for grain yield and secondary traits of Zn‐enhanced normal, provitamin A and quality protein maize (QPM) hybrids and estimated heterosis under combined heat and drought (HMDS) and well‐watered (WW) conditions. Responses of all secondary traits, except for the number of days to mid‐anthesis, significantly differed for HMDS and WW conditions. The contribution of heterosis to grain yield was highly significant under both management levels, although higher mid and high‐parent heterosis was observed under WW than HMDS conditions. However, the findings suggest that inbred line performance was the best determinant of hybrid performance under HMDS. Strong correlations were observed between grain yield and secondary traits for both parents and hybrids, and between secondary traits of inbred lines and hybrids under both management levels, indicating that hybrid performance can be predicted based on intrinsic inbred line performance. Phenotypic correlation between grain yield of inbred lines and hybrids was higher under HMDS than WW conditions. This study demonstrated that under HMDS conditions, performance of Zn‐enhanced hybrids could be predicted based on the performance of their corresponding inbred lines. However, the parental inbred lines should be systematically selected for desirable secondary traits correlated with HMDS tolerance during inbred line development.

Genotype by Environment Interaction on Early-Maturing and High-Yield Maize Hybrids

productivity in drylands in Indonesia. Trials of hybrid maize candidates in several locations and different seasons are highly needed to determine the stability of hybrid maize candidates prior to commercial release. The objectives of the research were: (1) to evaluate the performance of maize hybrids in several locations and different seasons; (2) to assess the stability of early-maturing and grain yield characteristics of genotypes evaluated in several locations and seasons; and (3) to determine hybrid maize candidates that can be released as new superior/elite varieties. The research was conducted at 14 research populations (7 different locations, 2 seasons). Each population was planted according to the randomized block design with 10 genotypes as treatments and 4 replicates, so 40 experiment units were obtained. Ten genotypes were tested: six hybrid maize candidates derived from a diallel cross with high yield potential and early-maturing traits (G1, G2, G3, G4, G5, G6) and 4 elite varieties as checks (G7 = SK, G8 = ANM, G9 = Pertiwi-x, and G10 = BISI-x). The combined analysis of variance (ANOVA) conducted on 10 genotypes and 14 research populations revealed that genotypes, environments (season, location, season x location), and interactions (genotype x season, genotype x location, genotype x season x location) significantly affect harvest age and grain yield per hectare (p < 0.01). G4 had an early harvest age (91.93 days) and grain yield per hectare above the average of all genotypes in all environments (8.71 ton ha-1), and was also declared stable based on three stability analyses: Finlay-Wilkinson, Eberhart-Russel, and AMMI. Thus, G4 is recommended as an elite hybrid maize variety with early-maturing, high-yield, stable, and broad adaptability traits. Doi: 10.28991/HEF-2023-04-01-05 Full Text: PDF

Performance of hybrid maize at different nitrogen levels in spring season at Badhaiyatal area of Bardiya District, Lumbini Province, Nepal

Blanket recommendation of nitrogen (N) for maize would not be applicable as the new high yielding hybridshave been grown in Nepal. A field experiment was carried out during spring season at Badhaiyatal, Bardiya to determine optimum N level for hybrid maize. The treatments consisted of three commercial maize hybrids namely Rampur hybrid-10, Rajkumar and Pioneer-3522 and four N levels i.e., 150 kg ha-1, 175 kg ha-1, 200 kg ha-1 and 225 kg ha-1. The experiment was carried out in split-plot design with maize hybrids as main plot factor and N levels as sub plot factor in three replications. Results revealed that all yield attributes were significantly (0.05) influenced by variety and nitrogen levels except number of ears harvested per hectare. The grain yield with N level @ 225 kg ha-1 (8.69 t ha-1) was found higher than remaining N levels. The higher yield with 225 kg N ha-1 was because of significantly (0.05) higher leaf area index (4.67 at 75 Days After Sowing, plant height (248.50 cm at 75 DAS), number of kernels per ear (467), ear length (18.59 cm), ear circumference (15.16 cm) and shelling percentage (70.68%). All three maize hybrids: Pioneer 3522 (8.46 tha-1), Rajkumar (8.05 t ha-1) and Rampur hybrid-10 (7.63 t ha-1) were found similar in grain yield. The yield attributes viz., ear length, and ear circumference number of kernels per ear showed positive correlation with grain yield. Therefore, application of N@ of 225 kg ha-1 for the maize hybrids during spring season is suggested in Bardiya.

Modeling the influence of phenotypic plasticity on maize hybrid performance

Phenotypic plasticity, the ability of an individual to alter its phenotype in response to changes in the environment, has been proposed as a target for breeding crop varieties with high environmental fitness. Here, we used phenotypic and genotypic data from multiple maize (Zea mays L.) populations to mathematically model phenotypic plasticity in response to the environment (PPRE) in inbred and hybrid lines. PPRE can be simply described by a linear model in which the two main parameters, intercept a and slope b, reflect two classes of genes responsive to endogenous (class A) and exogenous (class B) signals that coordinate plant development. Together, class A and class B genes contribute to the phenotypic plasticity of an individual in response to the environment. We also made connections between phenotypic plasticity and hybrid performance or general combining ability (GCA) of yield using 30 F1 hybrid populations generated by crossing the same maternal line with 30 paternal lines from different maize heterotic groups. We show that the parameters a and b from two given parental lines must be concordant to reach an ideal GCA of F1 yield. We hypothesize that coordinated regulation of the two classes of genes in the F1 hybrid genome is the basis for high GCA. Based on this theory, we built a series of predictive models to evaluate GCA in silico between parental lines of different heterotic groups.

Recent Advances in Breeding Maize for Drought, Heat and Combined Heat and Drought Stress Tolerance in Sub-Saharan Africa

Abstract Drought, heat, and combined drought and heat are important abiotic stresses constraining the production and productivity of maize ( Zea mays L.) in sub-Saharan Africa (SSA). In the face of climate change, these stresses are likely to occur simultaneously and put at risk food and economic security in SSA. This review describes maize breeding activities conducted by the International Institute of Tropical Agriculture (IITA) in partnership with national scientists under the Drought Tolerant Maize for Africa (DTMA) and Stress Tolerant Maize for Africa (STMA) projects, which together sought to develop and deploy multiple stress tolerant hybrids, and open-pollinated varieties. Emphasis was on (i) developing a reliable methodology for screening maize for tolerance to drought stress (DS), heat stress (HS), and combined drought and heat stress (CDHS) using key secondary traits and grain yield, (ii) use of appropriate breeding techniques for tailoring maize for tolerance to DS, HS and CDHS, (iii) exploring diverse sources of germplasm for genetic enhancement of maize, (iv) extensive multilocational evaluation to identify genotypes with stable performance under the stresses, and (v) application of genomic tools to accelerate genetic gains in maize breeding at IITA. At IITA, the performance of maize hybrids under stresses of DS, HS and CDHS have been improved using conventional breeding techniques/procedures. These techniques/ procedures have led to accelerated genetic gains in yield that were 26–49% higher than the best commercial hybrid checks under CDHS and DS. Additive gene action has been consistently found to be more important than the non-additive among early maize under DS and CDHS while both the additive and non-additive have been reported to be important for the extra-early maize. The most reliable secondary traits for selecting for improved grain yield under the stresses include anthesis-silking interval, ears per plant, and plant and ear aspects. Several early and extra-early landraces have been identified as potential sources of tolerance to DS, HS, and CDHS. Several quantitative trait loci (QTLs) associated with grain yield and key secondary traits have been identified via genome-wide association studies in landraces and inbred lines. Those desirable QTLs, upon validation, could be invaluable for genomics-enabled breeding.

Agronomic performance of maize hybrids influenced by sowing dates and plant spacing

Agronomic performance of maize hybrids influenced by sowing dates and plant spacing

Agronomic Performance of Maize Hybrids Influenced by Sowing Dates and Plant Spacing

A field experiment was conducted during Kharif, 2020 at Agronomy Research Farm, Faculty of agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology, Wadura, Sopore in Split- split plot design with three dates of sowing viz; 17th SMW (D1), 19th SMW (D2) and 21st SMW (D3) as main plot treatments, three varied row spacing viz; 50 cm×20 cm (S1), 60 cm × 20 cm (S2) and 70 cm×20 cm (S3) as sub- plot treatments and two maize hybrids viz; Hytech- 5801 and YSH- 1 as sub- sub plot treatments. The conclusion of the demonstration showed that growth parameters viz., plant height, dry matter production, LAI, functional leaves per plant increased significantly for the crop sown on 17th SMW(D1) with a concomitant increase in its yield attributing factors, ie., cob length, cob girth, number of grains per cob and test weight and yield. The growth, yield and yield attributing factors also recorded highest values with a plant spacing of 70 cm× 20 cm (S3). As far as hybrids are concerned, growth characters showed significant and consistent increase in hybrid Hytech-5801 (H1) compared to hybrid YSH-1 (H2) with an associated increase in yield and yield attributing factors.

Effect of soil moisture conservation practices and foliar fertilization on the performance of hybrid maize (Zea mays) under Cauvery Delta Zone of India

One of the crucial variables that affects the growth and yield of the maize crop is soil moisture. Soil mulching and foliar nutrition are significantly impacted by the absence of moisture in the soil, which has a favourable impact on the growth and yield of the crops. With this background, a field experiment was conducted during kharif 2020 at Annamalai University, Tamil Nadu, India to maximize the productivity and profitability of maize by adopting various soil moisture conservation techniques and foliar fertilization. The experiment was laid out in factorial randomized block design (FRBD) with three replications. The experiment consisted of two factors comprising soil moisture conservation techniques viz., sugarcane trash, water hyacinth, hydrogel and control (no mulch plot), and foliar nutrient management practice at both knee high and tasseling stages using 19 : 19 : 19 1%, DAP 1%+MOP 1%, PPFM (Pink pigmented facultative methylotrophs) 1%, 19 : 19 : 19 1%+PPFM 1%, DAP 1%+MOP 1%+PPFM 1% and control (no foliar nutrition). Among the soil moisture conservation techniques, the results indicated that mulching with water hyacinth registered significantly higher yield parameters, yield and economic returns than other techniques. With regards to foliar nutrients, foliar application of DAP 1%+MOP 1%+PPFM 1% (F6) exhibited higher yield parameters, yield and economic returns than other foliar nutrient treatments. Therefore, integration of soil moisture conservation techniques and foliar nutrients, mulching with water hyacinth and foliar application of DAP 1%+MOP 1%+PPFM 1% (M3F6) significantly produced higher yield parameters, yield and economic benefits in maize cultivation.

ECONOMIC EFFICIENCY IN CULTIVATION OF MAIZE HYBRIDS OF DIFFERENT GROUPS OF MATURITY IN CONDITIONS SRF «AHRONOMICHNE»

The article reflects the results of the research conducted with studies on the performance of maize hybrids and shows the economic efficiency of cultivation of different maize hybrids depending on mineral fertilizer. Mineral fertilisers are the most important element in the technology of growing new maize hybrids Therefore it is very important to study the effect of fertilizers. Therefore, it is very important to study the effect of fertilizers on grain productivity corn hybrids, which are most common in our region and important economic importance. The aim of the research was to analyze influence and interrelation of productivity and economic efficiency cultivation of maize hybrids. Ukrainian agrarians traditionally grow maize for grain, and it occupies a significant place in the structure of grain production. In recent years In recent years, all agricultural producers note a sharp increase in gross yield The crop has been appreciated as one of the most important high-yielding and versatile cereal crops Cereals with a versatile purpose, which are grown for food, fodder and technical purposes, Forage and technical uses In Ukraine maize is used for both food and feed purposes. both for food and technical purposes, as well as for the feed industry. fodder production. An important area of sustainable development of the global Farming is one of the most important areas of sustainable global economic development at the beginning of the 21st century. An important element of sustainable development in global economic development in the beginning of the 21st century, including in the agricultural sector, is the improvement and implementation of new resource-, energy-saving and environmentally friendly technologies. It is proved that use of mineral fertilizers has a positive impact on for formation of grain productivity indicators of maize hybrids. What can be noted with the following statement, the more nitrogen fertilizers were applied the more was the yield. When comparing to the variant without fertilizer corn hybrids yield increased by 83-90% and amounted to 12,18-12,88 t/ha. From this we can conclude that the most promising fertilization system for maize hybrids is the application of cultivation of N128P128K128 with a subsequent addition of nitrogen in a dose of N70 in the phase of 6- 7 leaves of maize providing a gross yield of 12.18-12.88 t/ha of grain with an level of profitability of production 219-232%. In addition it is indicated in the publication of the main aspects of the technology of growing maize on grain, which underlie the improvement of production efficiency indicators first of all, yield, profit and level of profitability.

Comparison of sequencing-based and array-based genotyping platforms for genomic prediction of maize hybrid performance

Genomic selection (GS) is a powerful tool for improving genetic gain in maize breeding. However, its routine application in large-scale breeding pipelines is limited by the high cost of genotyping platforms. Although sequencing-based and array-based genotyping platforms have been used for GS, few studies have compared prediction performance among platforms. In this study, we evaluated the predictabilities of four agronomic traits in 305 maize hybrids derived from 149 parental lines subjected to genotyping by sequencing (GBS), a 40K SNP array, and target sequence capture (TSC) using eight GS models. The GBS marker dataset yielded the highest predictabilities for all traits, followed by TSC and SNP array datasets. We investigated the effect of marker density and statistical models on predictability among genotyping platforms and found that 1K SNPs were sufficient to achieve comparable predictabilities to 10K and all SNPs, and BayesB, GBLUP, and RKHS performed well, while XGBoost performed poorly in most cases. We also selected significant SNP subsets using genome-wide association study (GWAS) analyses in three panels to predict hybrid performance. GWAS facilitated selecting effective SNP subsets for GS and thus reduced genotyping cost, but depended heavily on the GWAS panel. We conclude that there is still room for optimization of the existing SNP array, and using genotyping by target sequencing (GBTS) techniques to integrate a few functional markers identified by GWAS into the 1K SNP array holds great promise of being an effective strategy for developing desirable GS breeding arrays.

Influence of intra-row spacing on improved maize variety at Dambi Dollo University Research Site, Western Ethiopia

Maize (Zea mays L.) is one of the greatest significant grain crops in Ethiopia which ranked second only next tef in local production. However, its production is limited due to incorrect line spaces between crops. Therefore, field research was conducted at Dambi Dollo University during the 2020/2021 growing season under irrigated conditions for the production and yield of hybrid maize (BH546) with the help of optimizing spaces between rows. The test is performed using a three-dimensional Random Block Design with three replication in a single-factor test having three different line spaces (20 cm, 30 cm and 40 cm). The highest values ​​of total ears in each crop, length of the ears, total seed rows in each cob, seed in each cob, the weight of a thousand grains, seed yield, and the harvest index are recorded in wide spaces (40 cm). The performance of hybrid maize (BH546) and part of the crop, a wide range of 40 cm rows between crops can be recommended in the study area.

Response of Different Levels of Nitrogen and Plant Population to Grain Yield of Winter Hybrid Maize in Chitwan Valley

A field experiment on “Performance of hybrid maize under different levels of nitrogen and plant population” was conducted in Randomized complete block design (RCBD) at the research farm of the National Maize Research Program (NMRP), Rampur, Chitwan during the winter season of 2015/16 to determine the optimum level of nitrogen and plant population for winter season hybrid maize. The grain yield (2.38 Mt ha-1) obtained in control without nitrogen was significantly lower in comparison to its all other levels (70, 140 and 210 Kg N ha-1). Moreover, grain yield (5.45 Mt ha-1) produced by the application 210 Kg N ha-1 was significantly superior over 70 Kg N ha-1 (3.83 Mt ha-1) but remained at par with 140 Kg N ha-1 (5.02 Mt ha-1) which also differed significantly. Moreover, the grain yield (4.98 Mt ha-1) recorded with the population of 101010 plants ha-1 was significantly superior over 55,555 (3.34 Mt ha-1) and 69,444 (3.90 Mt ha-1) plants ha-1 but similar to that of 85,470 plants ha-1 (4.46 Mt ha-1) which was also significantly higher as compared to 69,444 and 55,555 plants ha-1 which were at par with each other. Regression analysis for the effect of nitrogen and plant population on grain yield showed the grain yield was 145 Kg N ha-1 and plant population was 87445 plants ha-1. Thus, hybrid maize (RML95/RML96) can be successfully grown by applying 145 Kg N ha-1 and maintaining a population of 87 thousand plants ha-1 to achieve a higher grain yield during the winter season.

Dissection of the Genetic Basis of Yield Traits in Line per se and Testcross Populations and Identification of Candidate Genes for Hybrid Performance in Maize.

Dissecting the genetic basis of yield traits in hybrid populations and identifying the candidate genes are important for molecular crop breeding. In this study, a BC1F3:4 population, the line per se (LPS) population, was constructed by using elite inbred lines Zheng58 and PH4CV as the parental lines. The population was genotyped with 55,000 SNPs and testcrossed to Chang7-2 and PH6WC (two testers) to construct two testcross (TC) populations. The three populations were evaluated for hundred kernel weight (HKW) and yield per plant (YPP) in multiple environments. Marker–trait association analysis (MTA) identified 24 to 151 significant SNPs in the three populations. Comparison of the significant SNPs identified common and specific quantitative trait locus/loci (QTL) in the LPS and TC populations. Genetic feature analysis of these significant SNPs proved that these SNPs were associated with the tested traits and could be used to predict trait performance of both LPS and TC populations. RNA-seq analysis was performed using maize hybrid varieties and their parental lines, and differentially expressed genes (DEGs) between hybrid varieties and parental lines were identified. Comparison of the chromosome positions of DEGs with those of significant SNPs detected in the TC population identified potential candidate genes that might be related to hybrid performance. Combining RNA-seq analysis and MTA results identified candidate genes for hybrid performance, providing information that could be useful for maize hybrid breeding.

Contribution of temperate germplasm to the performance of maize hybrids under stress and non-stress environments in South Africa

Increases in genetic gains are crucial to maize breeding programmes. The objectives of this study were to identify higher-yielding and stable maize hybrids across stress and non-stress environments, to identify representative test environments for testing and selection of superior maize genotypes, and to determine the contribution of temperate maize germplasm in the performance of new tropical hybrids. Respectively 42 and 72 newly developed single-cross hybrids together with check hybrids were evaluated separately for grain yield performance across stress and non-stress environments, at four locations (Potchefstroom, Cedara, Vaalharts/Taung and Makhathini) in South Africa, in the 2014/15 and 2015/16 growing seasons (seasons 1 and 2, respectively). Additive main effects and multiplicative interaction (AMMI) and genotype + genotype × environment interaction (GGE) biplots were employed. In season 1, the hybrids MO17HtHtN × CML444 and I-39 × CML444 were the most stable and high-yielding genotypes after the ideal commercial check. In season 2, the hybrids FO215W × CML444, I-42 × CML444 and U71Y × CML444 were stable and high-yielding, with FO215W × CML444 being the most ideal. These stable hybrids would be the best suited for wide adaptation across non-stress and stress environments. Hybrids containing tropical CIMMYT testers were more stable than those derived from temperate Corn Belt material. The locations Potchefstroom and Vaalharts were the most suitable environments for evaluating the performance of these genotypes across the diverse environments.

Genetic Dissection of Hybrid Performance and Heterosis for Yield-Related Traits in Maize.

Heterosis contributes a big proportion to hybrid performance in maize, especially for grain yield. It is attractive to explore the underlying genetic architecture of hybrid performance and heterosis. Considering its complexity, different from former mapping method, we developed a series of linear mixed models incorporating multiple polygenic covariance structures to quantify the contribution of each genetic component (additive, dominance, additive-by-additive, additive-by-dominance, and dominance-by-dominance) to hybrid performance and midparent heterosis variation and to identify significant additive and non-additive (dominance and epistatic) quantitative trait loci (QTL). Here, we developed a North Carolina II population by crossing 339 recombinant inbred lines with two elite lines (Chang7-2 and Mo17), resulting in two populations of hybrids signed as Chang7-2 × recombinant inbred lines and Mo17 × recombinant inbred lines, respectively. The results of a path analysis showed that kernel number per row and hundred grain weight contributed the most to the variation of grain yield. The heritability of midparent heterosis for 10 investigated traits ranged from 0.27 to 0.81. For the 10 traits, 21 main (additive and dominance) QTL for hybrid performance and 17 dominance QTL for midparent heterosis were identified in the pooled hybrid populations with two overlapping QTL. Several of the identified QTL showed pleiotropic effects. Significant epistatic QTL were also identified and were shown to play an important role in ear height variation. Genomic selection was used to assess the influence of QTL on prediction accuracy and to explore the strategy of heterosis utilization in maize breeding. Results showed that treating significant single nucleotide polymorphisms as fixed effects in the linear mixed model could improve the prediction accuracy under prediction schemes 2 and 3. In conclusion, the different analyses all substantiated the different genetic architecture of hybrid performance and midparent heterosis in maize. Dominance contributes the highest proportion to heterosis, especially for grain yield, however, epistasis contributes the highest proportion to hybrid performance of grain yield.

Agronomic performance of maize hybrids for forage production in the 2019/2020 harvest

Maize has great economic prominence in national and international agribusiness, being used for various purposes such as grain use and in the form of bulky (silage). This study aimed to evaluate the agronomic characteristics of twelve maize hybrids for silage production in Inconfidentes-MG. Twelve hybrids were used: 20A78PW, 2B512PW, 2B533PW, 2B688PW, 30F53LEPTERA, AG8740-PRO3, DKB345-PRO3, DKB363-PRO3, LG3055-PRO3, LG6036-PRO3, MAXIMUS-VIP3, and MG652PW. The treatments were implanted in a randomized block design (CBD) containing three repetitions. The experimental plots consisted of four lines of five meters in length and 0.8 m spacing between rows, with the two central lines as useful areas. The parameters evaluated were green matter productivity, dry matter productivity, plant height, ear height, average stalk thickness, cutting window, flowering, and cycle. The hybrids 20A78PW; 2B533PW; DKB345-PRO3, and DKB363-PRO3 presented the highest cut-off window values in relation to the others. LG3055-PRO3 hybrid presented the smallest cut-off window. The hybrids 30F53LEPTERA, AG8740, DKB345-PRO3, LG6036-PRO3, and MG652PW presented the highest plant height values. No statistical difference was observed between the hybrids for the variables: green matter productivity, ear height, and stalk thickness. Hybrids AG8740, DKB345-PRO3, LG6036-PRO3, and MG652PW obtained the highest dry matter productivity values. Hybrids 20A78PW, 2B533PW, DKB345-PRO3, and DKB363-PRO3 presented the lowest male and female flowering time. Hybrid DKB345-PRO3 stood out, showing great potential to be recommended and cultivated by silage producers.